Variable focal length lens systems are known. For example, U.S. Pat. No. 6,873,473 B2, issued Mar. 29, 2005, to Lewis et al., discloses a two position variable focal length lens. The variable focal length lens includes a common lens element moveably positioned on an optical axis; a wide angle lens element moveable between a first location removed from the optical axis and a first position on the optical axis on an image side of the common lens element; and a telephoto lens element moveable between a second location removed from the optical axis and a second position on the optical axis on the image side of the common lens element. A magnification ratio change occurs by moving the common lens element along the optical axis and switching between the wide angle lens element located at the first position on the optical axis and the telephoto lens element located at the second position on the optical axis.
U.S. Pat. No. 6,449,430 B1, issued Sep. 10, 2002, to Tasaka et al., discloses a lens-fitted photo film unit having a rotatable lens holder that supports first and second taking lenses arranged perpendicularly to a photographic optical axis. The first and second taking lenses have different focal lengths. An externally operable button rotates the lens holder to selectively position the first and second taking lenses on the photographic optical axis.
The first lens, a wide-angle taking lens, is located on an object side of a first aperture, and consists of two lens elements. The second lens, a telephoto taking lens, is located on an object side of a second aperture, and consists of a single lens element. When compared to the wide-angle taking lens, the telephoto taking lens is positioned offset toward the object side along the photographic optical axis. The second aperture is also positioned offset toward the object side along the photographic optical axis when compared to the first aperture.